Automotive interior components such as automotive door trims, rear side trims, rear parcel shelves, etc. are typically provided with a layered structure comprising a core layer having a certain rigidity and a skin layer having an ornamental or attractive surface texture which is bonded to the surface of the core layer. Conventionally, an interior component part of a desired shape was obtained by softening a thermoplastic resin plate or a thermoplastic composite resin plate, serving as a core layer, by heating it, laminating a skin layer consisting of a sheet of non-woven fabric or resin material over the core layer, and cold press forming this assembly.
To the end of reducing the labor and the time required for manufacturing such interior components, a certain method was proposed in Japanese Patent Publication No. 61-32142. According to this metod, an exterior sheet 1 is placed on a lower press mold 3 and blocks of thermoplastic resin material 2, for instance, consisting of polyolefin resin material or the like, are placed on the exterior sheet 1 as shown in FIG. 5. Then, an upper press mold 4 is lowered over the lower press mold 3 and they are clamped together to squeeze the thermoplastic material 2 into a sheet therebetween as shown in FIG. 6. As a result, the exterior sheet 1 and the thermoplastic material 2 are integrally bonded together and this assembly is given a desired shape as shown in FIG. 7.
To the end of achieving a satisfactory bonding between the core layer which typically consists of polyolefin resin and the exterior sheet having a poor mutual bonding capability, the reverse surface of the exterior sheet 1 is typically laminated with a fibrous layer 1b' consisting of fibrous material such as a non-woven fabric lining.
This method can achieve a considerable saving in labor but the material of the exterior sheet 1 is limited to non-porous resin sheet material such as a polyvinyl chloride sheet and, if a porous material such as cloth, carpet, non-woven fabric etc. is used, the excessive clamping pressure would cause the molten resin material to infiltrate through the space between the fibers of the exterior sheet to the external surface, thereby severely impairing the external appearance of the assembly.
Thus, according to this conventional method, the skin layer is required to be made of non-porous material and a severe restriction is therefore imposed on material selection.
Further, for press forming blocks of thermoplastic resin material into a sheet, a considerably high pressure and temperature are required so that the thermoplastic resin material tends to infiltrate through the fibrous material and, although a strong bonding may be achieved by the interlocking of the two materials, the surface of the exterior sheet 1 suffers from surface irregularities due to the infiltration of the thermoplastic resin into the space between the fibers of the exterior sheet, thus impairing the appearance and the fuel of the external surface.